https://gcc.gnu.org/g:11cc336eed42892b7cfc2bfcf7b3f3f86f61787a
commit r15-7567-g11cc336eed42892b7cfc2bfcf7b3f3f86f61787a
Author: Keith Packard <kei...@keithp.com>
Date: Sat Feb 15 09:17:41 2025 -0700
[PATCH] rx: allow cmpstrnsi len to be zero
The SCMPU instruction doesn't change the C and Z flags when the
incoming length is zero, which means the insn will produce a
value based upon the existing flag values.
As a quick kludge, adjust these flags to ensure a zero result in this
case.
gcc/
* config/rx/rx.md (rx_cmpstrn): Correctly handle len=0 case.
Diff:
---
gcc/config/rx/rx.md | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/gcc/config/rx/rx.md b/gcc/config/rx/rx.md
index 89211585c9ce..edb2c96603f5 100644
--- a/gcc/config/rx/rx.md
+++ b/gcc/config/rx/rx.md
@@ -2590,7 +2590,9 @@
(clobber (reg:SI 3))
(clobber (reg:CC CC_REG))]
"rx_allow_string_insns"
- "scmpu ; Perform the string comparison
+ "setpsw z ; Set flags in case len is zero
+ setpsw c
+ scmpu ; Perform the string comparison
mov #-1, %0 ; Set up -1 result (which cannot be created
; by the SC insn)
bnc ?+ ; If Carry is not set skip over
